<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .outer{
width: 500px;
height: 300px;
background-color: pink;
margin: 0 ;
padding-top: 200px;
    }
    .inner{
width: 100px;
height: 100px;
background-color: green;
margin: 0 auto;
text-align:center;
line-height:100px;
    }
</style>
<body>
    <div class="outer">
        <div class="inner">
            inner
        </div>
    </div>
</body>

</html>